This invention relates to a thermal recording device in which data are thermally recorded using at least two thermal heads or heat generating unit arrays.
In some thermal recording devices in which data are recorded in multicolors or with high resolution, data are thermally recorded using at least two thermal heads or heat generating unit arrays.
One example of a two-color recording device of this type is as shown in FIG. 1. The device comprises a first recording section A for recording data in a red recording color and a second recording section B for recording data in a black recording color, for example. The recording sections A and B have thermal heads 1A and 1B, respectively. The thermal head 1A is driven by red image signals. An ink donor sheet 3A coated with a thermal transfer type ink is supplied from a supply roll 2A to the thermal head 1A, so that "red" data are thermally transferred in a red recording color to a recording sheet 4 which runs in the direction of the arrow. A back roll 5A operates to press the recording sheet 4 against the ink donor sheet 3A to facilitate the thermal transfer of the ink and to convey the recording sheet 4. After the thermal transfer operation has been accomplished, the used ink donor sheet 3A is wound on a winding roll 6A.
Similarly, as in the first recording section A, in the second recording section B an ink donor sheet 3 is conveyed from ;a supply roll 2B to a winding roll 6B, and data are thermally recorded in black on the recording sheet, which passes between a thermal head 1B and a back roll 5B. In order to miniaturize the memory for delaying the image signals, for example, the distance between the two recording sections A and B is made as short as possible. Therefore, the recording operations of the two recording sections A and B overlap each other in time.
FIG. 2 shows a thermal head used in a thermal recording device which is high in resolution. Two arrays of heat generating elements 11 and 12 are arranged on the insulated substrate 9 of the thermal head 8 in such a manner that they are in parallel with each other and are shifted by 1/2 pitch in the "column" direction. The array of heat generating elements 11 is divided into two blocks of heat generating elements by first common electrodes 13A and 13B, and the array of heat generating elements 12 is divided into two blocks of heat generating elements by second common electrodes 14A and 14B. When image signals are supplied to individual drive electrodes 15 and 16, the blocks of heat generating elements are driven separately. Thus, the distribution of image signals for a line of an original to two arrays of heat generating elements 11 and 12 makes it possible to thermally record data with high resolution. In this case also, the recording operations of the two arrays 11 and 12 are overlapped in time.
A thermal recording device in which a plurality of thermal heads or plural arrays of heat generating units (or heat generating elements) are driven simultaneously requires a power source of large capacity. Therefore, such devices are disadvantageous in that their manufacturing cost is high.